During the cellulose derivatization process, hemicellulose is known as the main reason for the deterioration of final product quality and processability problems such as poor filterability, increased viscosity, and discoloration. Therefore, dissolving pulp with high cellulose purity and reactivity is required for the production of cellulose derivatives. Typically less than 1.5% of residual hemicellulose is required for cellulose acetate grade to avoid the haze and color formation. However, the detailed mechanism on how hemicellulose affects this deteriorating issue is not fully understood and it is only known by practical experience. To understand the chemical and structural characteristics of residual hemicellulose, we have extracted hemicellulos in dissolving pulps by two-stage alkaline extraction. It was found that refining treatment and cold-temperature extraction enhanced hemicellulose extraction. Compared to the extraction from unrefined dissolving pulp at a room temperature, hemicellulose extraction yield was improved up to four times. Also, their effects on the carbohydrate composition and molecular weight of extracted hemicellulose were studied. Glycosidic linkage analysis revealed that structural conformation of residual hemicellulose was greatly differed among the different dissolving pulps. Some of the extracted xylan retained their branched structure, while others showed almost complete linear structure. Commercial xylan products were also analyzed as a control. The findings from this study will provide useful information not only for the dissolving pulp research, but also for all the field of hemicellulose utilization.

Extraction and characterization of residual hemicellulose in dissolving pulp

255th National Meeting (2018)

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